The idea that the letters of a sacred alphabet are the building blocks of reality, and that their combination and numerical value reveal hidden truths, runs through Kabbalah, Islamic letter mysticism (ilm al-huruf), and Greek and Gnostic speculation. In the Western magical tradition the Hebrew letters are also mapped onto the paths of the Tree of Life and the tarot trumps.
The atlas gives each letter its name, sound, numerical value and correspondences. The letters group by alphabet (Hebrew, Greek, runic, Enochian and the rest), and the ogham letters, grouped into aicmi, and the runes are also treated in their own categories.